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Finding the Andromeda Galaxy in the night sky


The Andromeda Galaxy, also known as M31, is the most distant object that the unaided human eye can see; it lies over 2.2 million light years away. Locating it the first time is a little tricky, but once you find it, it's hard to ever lose it again.

Steps

  1. You will need to locate three constellations, Pegasus, Cassiopeia and Andromeda (This chart shows the night sky for 35°N and is set for the 1st of December at 8:00 pm local, but can be used for later in the evening before that date and earlier after). The best time to find the Andromeda Galaxy is between August through late March.
  2. Pegasus is one of the easier to locate of the three, as it looks like a giant rectangle; this is the Great Square of Pegasus. Cassiopeia is even easier to locate, looking like a giant "M" or "W". Andromeda lies between them.
  3. Draw a line from the star Sirrah (also known as Alpheratz) on the edge of Pegasus and Andromeda to the star Ruchbah in Cassiopeia.
  4. Draw a line from Mirach through mu Andromedae and on through the first line. Keep in mind that mu Andromedae is dimmer than Mirach.
  5. Scan the area just to the southeast of where the lines meet, along the second line, with binoculars or a small telescope. You'll notice an oval of faint light. This is the Andromeda Galaxy.

Tips

  • The Andromeda Galaxy can be seen even in relatively bright skies, but it might be a little harder to locate some of the fainter stars, so you may need to scan a slightly larger area.
  • For your first attempt, use binoculars. This will make it significantly easier.
  • If you look carefully in binoculars or a telescope, you may find two faint fuzzy spots beside it. One of them, M32, is smaller in size and closer to the actual galaxy core. The other, NGC 205, is more elusive, larger in size, and farther from the actual galaxy. Both are companion galaxies to Andromeda
  • You will probably be able to find it if you use a GOTO or computerised telescope. If you use an equatorial and know how to use setting circles, the Galaxy is at RA 00h43m, DEC +41deg16' .
  • In the opposite direction from the three/four bright stars, you may find two bright stars, and another faint star the appears as a double, which a triangle. If you draw a line from the faint star to the spot in-between the two brighter stars, and keep going, you may find the Triangulum Galaxy, another bright but highly elusive galaxy.
  • What you actually see is the core of the galaxy, the outer arms are very faint. You might wish to try to photograph it to make it show up, but you will likely need a long exposure time, a camera adapter, and image stacking software such as RegiStax or ImagesPlus.
  • If you are able to observe in a dark area away from streetlights, you are more likely to be able to find this object.

Warnings

  • Remember to dress for the weather, especially in the colder months.
  • This may be difficult to do in the southern hemisphere.

Things You'll Need

  • Binoculars and/or telescope
  • Camera and Star Atlas/Planisphere (optional)

Related wikiHows

Sources and Citations

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